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Hello,
First of all, i would like to say that i tried to solve my problem using the manual, FAQ's and the Hotline from Siemens, and i'm afraid i have to bother you experts.
I'm developing a network between a S7-200 PLC and a V20 Inverter.
Both devices are working properly, perfectly functional.
Physical installation:
I used a shielded cable with a db9 conector in the Port 0 of the PLC and other end of the cable a 3 wire connection in the V20 terminal.The wires that i welded in the db9 conector were the 3, 5 and 8... following the scheme from the S7-200 manual (attach1)
In the inverter's terminal i conected: wire 8 in the N- terminal and the wire 3 in the P+. The Hotline support told me not to connect the wire 5 in the inverter's GND, but to connect the "M" (0V from the power supply and the 0V of the CLP) with the GND of all system. After that the specialist told me to put GND in all 0V terminals of the V20 Inveter (terminal 5 and 14).
Programming:
The Modbus function blocks that i used in this progrem are described in the second attachment. Of course its not the hole program, but the essencial part of the comunication. I used a 9.6 BaudRate, and it was also configured in the V20 inverter by the parameter P2010;
Timeout of 1000ms and also configured in the inverter (P2022);
Selected Modbus in P2023 parameter;
Slave address 4 was also configured in the inverter by the P2021 parameter;
The inicial test of this application was just to Read the speed of a motor, so RW=0, and Addr=40024 (following the mapping table -third attachment-).
After all theses configurations, i just had Error Code Number "3", that means the slave wasnt found.
Anyone have any idea why this isnt working properly?
Anything wrong with these conections?
Thanks a lot!